ISO 20421-1:2019

INTERNATIONAL ISO
STANDARD 20421-1
Second edition
2019-06
Cryogenic vessels — Large
transportable vacuum-insulated
vessels —
Part 1:
Design, fabrication, inspection and
testing
Récipients cryogéniques — Récipients transportables isolés sous vide
de grande contenance —
Partie 1: Conception, fabrication, inspection et essais
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 5
5 General requirements . 7
6 Mechanical loads . 7
6.1 General . 7
6.2 Load during the pressure test . 7
7 Chemical effects . 8
8 Thermal conditions . 8
9 Materials . 8
9.1 Selection of materials . 8
9.2 Inspection documentation . 8
10 Design . 9
10.1 Design options . 9
10.1.1 General. 9
10.1.2 Design by calculation . 9
10.1.3 Design by calculation and pressure strengthening . 9
10.1.4 Design of components by calculation supplemented with experimental methods 9
10.2 Common design requirements . 9
10.2.1 General. 9
10.2.2 Design specification .10
10.2.3 Design loads .11
10.2.4 Fatigue .15
10.2.5 Corrosion allowance .15
10.2.6 Inspection openings .16
10.2.7 Pressure relief .16
10.2.8 Valves .17
10.2.9 Insulation .17
10.2.10 Degree of filling .17
10.2.11 Electrical continuity .17
10.3 Design by calculation .17
10.3.1 General.17
10.3.2 Inner vessel .17
10.3.3 Outer jacket .20
10.3.4 Attachments .21
10.3.5 Piping and accessories .21
10.3.6 Calculation formula .21
10.3.7 Calculations for operating loads .45
11 Fabrication .46
11.1 General .46
11.2 Cutting .46
11.3 Cold forming .46
11.3.1 Austenitic stainless steel .46
11.3.2 Ferritic steel .47
11.3.3 Aluminium or aluminium alloy .48
11.4 Hot forming .48
11.4.1 General.48
11.4.2 Austenitic stainless steel .48
11.4.3 Ferritic steel .48
11.4.4 Aluminium or aluminium alloy .48
11.5 Manufacturing tolerances .48
11.5.1 General.48
11.5.2 Plate alignment .49
11.5.3 Thickness .50
11.5.4 Dished ends .50
11.5.5 Cylinders .50
11.6 Welding .53
11.6.1 General.53
11.6.2 Qualification .53
11.6.3 Temporary attachments .53
11.6.4 Welded joints .53
11.7 Non-welded joints .54
12 Inspection and testing .54
12.1 Quality plan .54
12.1.1 General.54
12.1.2 Inspection stages during manufacture of an inner vessel .54
12.1.3 Additional inspection stages during manufacture of a large transportable
cryogenic vessel .55
12.2 P
...